Receptor Occupancy Research Articles

Investigating the novel CD16A and epidermal growth factor receptor (EGFR) bispecific innate cell engager, AFM24, to leverage the innate immune system: Interim results from the colorectal cancer (CRC) cohort.

e14508 Background: AFM24 is a tetravalent, bispecific innate cell engager that binds EGFR on solid tumors and CD16A on natural killer (NK) cells. AFM24 redirects NK cells to EGFR-expressing (EGFR+) solid tumors, enhancing antibody-dependent cellular cytotoxicity. AFM24 induced lysis of EGFR+ tumor cell lines in vitro independent of EGFR expression level and mutation status. The dose escalation phase (Phase 1) of the presented study (NCT04259450) previously established the recommended Phase 2 dose at 480 mg based on tolerability, receptor occupancy, and pharmacokinetics. Correlative science data revealed an activation and enrichment of immune cells in the tumor microenvironment. Here we present preliminary data from the Phase 2a CRC expansion cohort. Methods: The Phase 2a expansion phase is evaluating 480 mg AFM24 in patients with histologically or cytologically confirmed microsatellite stable, RAS wild type EGFR+ CRC. Patients have relapsed or refractory disease to ≥2 prior lines of therapy including an EGFR targeted therapy. EGFR+ is defined as positive staining for EGFR in ≥1% of tumor cells per local immunohistochemistry assay. The study follows Simon’s two-stage design. The primary endpoint is the overall response rate per RECIST v1.1 by investigator assessment; secondary endpoints include safety and tolerability; efficacy per iRECIST is exploratory. AFM24 is administered intravenously once weekly in a 28-day cycle. Tumor assessments are performed at screening, cycles 2, 4, 6, 8, and every 3 cycles thereafter. Results: As of December 2022, 16 patients with Stage 4 CRC were enrolled and treated with 480 mg AFM24 in the study. The median (range) age was 66 years (51–77); 11 males and 5 females; 9 Asian, 7 White). The median number of prior therapies was 4 (2–7) and the median treatment duration was 5.1 weeks (1.0–22.0). Treatment-related adverse events (TRAEs) were reported in 14/16 patients; infusion-related reactions (IRRs, 12), pruritus (3), lymphopenia (3), and anemia (2) were the most common. AFM24 TRAEs of Grade ≥3 occurred in 6 patients and included lymphopenia (3), decreased neutrophil count (1), increased blood bilirubin (1) and IRRs (1). To date, no objective responses were observed. Seven patients remain on treatment including 1 patient with confirmed stable disease ongoing for 5 months exhibiting a tumor reduction of –17%. Final interim results will be presented. Conclusions: The novel mechanism of action of AFM24 may provide an alternative treatment approach for patients with EGFR+ solid tumors. In this study, AFM24 monotherapy was adequately tolerated in a heavily pretreated population of patients with EGFR+ CRC. AFM24 is also being investigated in combination with atezolizumab and autologous NK cells in various EGFR+ solid tumors. Clinical trial information: NCT04259450 .

Leveraging innate immunity with AFM24, a novel CD16A and epidermal growth factor receptor (EGFR) bispecific innate cell engager: Interim results for the non-small cell lung cancer (NSCLC) cohort.

2533 Background: Patients with EGFR mutant NSCLC who progress on or after small molecule EGFR inhibitors have only limited treatment options. AFM24 is a tetravalent, bispecific innate cell engager that binds EGFR on solid tumor cells and CD16A on NK cells to redirect and enhance antitumor antibody-dependent cellular cytotoxicity, thus acting independently of the EGFR downstream signaling pathway and EGFR expression levels. The Phase 1 dose escalation phase of the presented study (NCT04259450) established the recommended Phase 2 dose of AFM24 monotherapy at 480 mg based on tolerability, receptor occupancy, and pharmacokinetics (PK). Correlative science data revealed an activation and enrichment of immune cells in the tumor microenvironment. Methods: The Phase 2a expansion phase is evaluating 480 mg AFM24 in patients with EGFR mutant NSCLC, relapsed or refractory to ≥1 prior lines of therapy; EGFR-positivity is defined as positive staining for EGFR in ≥1% of tumor cells per local immunohistochemistry assay. The study follows Simon’s two-stage design. The primary endpoint is overall response rate per local RECIST v1.1; secondary endpoints include safety, PK, and immunogenicity. Efficacy per iRECIST is an exploratory endpoint. AFM24 is administered intravenously once weekly in a 28-day cycle. Tumor assessments are performed at initial screening, cycles 2, 4, 6, 8, and every 3 cycles thereafter. Results: As of December 2022, 14 patients (median [range] age 55 [37–82]; 12 male; 11 Asian, 3 White) were enrolled; the median number of prior therapies was 2.5 (1–12). Median treatment duration with AFM24 was 6.7 weeks (1.0–26.1). Best objective response in 10 evaluable patients was confirmed partial response in 1 patient (change from baseline –45%); 4 patients exhibited stable disease, 1 was confirmed. Tumor shrinkage occurred in 2 patients with stable disease (–6%, –18%). The tumor control rate was 50%. Treatment-related adverse events (TRAEs) were reported in 13 patients; infusion related reactions (IRRs, 12), dermatitis acneiform, neutrophil count decreased, decreased appetite, and myalgia (2 each) were most common. Grade ≥3 TRAEs occurred in 4 patients and included decreased neutrophil count (2), lymphopenia, and IRR (1 each). Grade 5 pneumonitis was observed in 1 patient with disease progression and multiple comorbidities; relation to AFM24 could not be ruled out. As of January 2023, enrollment is ongoing; results of the interim analysis will be presented. Conclusions: AFM24 demonstrated clinical activity and acceptable safety in heavily pretreated patients with EGFR mutant NSCLC. The novel mechanism of action of AFM24 could add to the therapeutic options for patients with EGFR expressing tumors and is under clinical evaluation as a single agent and in combination with atezolizumab or autologous NK cells. Clinical trial information: NCT04259450 .

Phase 1 first-in-human study of PF-07257876, a novel CD47/PD-L1 bispecific checkpoint inhibitor, in patients with PD-1/PD-L1-refractory and -naïve advanced solid tumors.

2529 Background: Tumor expression of the antiphagocytic protein CD47 (integrin associated protein) may lead to immunotherapy resistance (IO-R). PF-07257876 is a novel, IgG1, Fc-active, bispecific antibody targeting CD47 and PD-L1 designed to reverse IO-R, decrease anemia risk, and eliminate a priming dose. We report a Phase 1 dose escalation study (NCT04881045) in patients (pts) with advanced solid tumors, both IO-refractory and IO-naïve. Methods: The study enrolled pts ≥18 yrs with advanced non–small-cell lung carcinoma (NSCLC) and squamous cell carcinoma of the head and neck (SCCHN) with PD-L1 expression >1% post anti-PD-1/PD-L1 therapy. Pts with other PD-L1+ tumors known to express CD47 were included (prior IO not required). Pts received PF-07257876 at escalating dose levels in 28-day cycles. Primary objectives were safety (dose-limiting toxicity [DLT] rate), tolerability, and determination of Recommended Phase 2 Dose (RP2D). Secondary and exploratory objectives included pharmacokinetics (PK), blood receptor occupancy (RO), CD47 levels by immunohistochemistry (IHC), tissue biopsy findings, and objective response rate (ORR) per RECIST v.1.1. Results: As of 20OCT2022, 18 pts were enrolled (NSCLC: n = 6; SCCHN: n = 4; other: n = 8). Median (range) age 68 (46–79) yrs. PF-07257876 was given at ascending doses, 150-2400 mg by subcutaneous (SC) injection or SC infusion every 2 weeks. 16 (89%) pts had treatment-related adverse events (TRAEs): Grades 1/2: n = 12 (67%); Grade 3: n = 1 (6%); Grade 4: n = 3 (17%); no Grade 5. Most common TRAEs: injection site reaction/erythema (n = 13, 72%), thrombocytopenia (n = 6, 33%), anemia (n = 5, 28%), and nausea (n = 4, 22%). DLTs occurred in 2 of 3 pts at the highest tested dose (Grade 4 neutropenia and thrombocytopenia, n = 1; Grade 4 thrombocytopenia, n = 1; both pts recovered). One pt with IO-R SCCHN had a confirmed partial response (duration of response 16 wks). ORR was 5.6% (1/18). Drug exposure increase after 1st dose was not dose proportional. Blood RO was > 95% for PD-L1 and > 70% for CD47 with drug exposure. All pts’ baseline CD47 IHC levels were moderate to high. Pharmacodynamics cytokine profiling showed notable dose-response increases of IFNg, TNFa, CXCL9/10, CCL3/4, without IL-6 increase. Conclusions: PF-07257876 was well tolerated with manageable toxicity. Incidence and grade of anemia or thrombocytopenia were manageable. Target engagement of CD47 and PD-L1 in peripheral blood was high. Innate and adaptive cytokine modulation was observed. Antitumor activity was modest. Expansion is ongoing at 1800 mg. Clinical trial information: NCT04881045 .

REFINE-Lung: A multicentre phase III study to determine the optimal frequency of pembrolizumab in non-small cell lung cancer utilising a novel multi-arm design.

TPS9145 Background: Pharmacological and clinical data suggest standard regimens for anti-PD1 agents nivo and pembro result in overtreatment. These agents have high target affinity, saturate PD1 at very low concentrations and maintain receptor occupancy for up to 30 wks following discontinuation. Clinical studies suggest no dose-response relationship in the wide range tested (0.1 – 10 mg/kg) and retrospective data suggest the efficacy of lower doses or longer administration frequency. Given their high costs and important implications for pt quality of life and toxicity, new approaches to optimise treatment regimens are required. However, conventional 2-arm non-inferiority designs require large numbers of patients, explore a single alternative to the standard of care and potentially require multiple trials to establish optimal parameters such as dose or frequency. Here we present a new multi-arm trial design to tackle this problem, implemented in the UK multicentre phase III REFINE-Lung study that aims to determine the optimal treatment frequency of pembro in NSCLC. Pts who are progression free after 6 months of standard therapy are randomised to 5 pembro frequency reduced arms (q6w, q9w, q12w, q15w and q18w). By evaluation of the frequency-response relationship, we will determine the longest frequency that is equivalent to standard of care within a pre-defined margin. Methods: The REFINE-Lung trial (NCT05085028) is a multicentre, randomised open-label, phase III trial in advanced NSCLC. REFINE-Lung utilises a novel Multi-Arm Multi-Stage Response Over Continuous Interventions (MAMS-ROCI) design to determine the optimal dose frequency of pembro. 1750 pts aged ≥18 and progression free at six months into 1st line pembro and planning to continue, will be enrolled from up to UK 35 hospital groups. Pts will be randomised across 5 arms to determine the optimal dose frequency. To assess safety, pts will initially be randomised 1:1 into q6w (control) and q12w arms. Interim analysis will be conducted once 37 progression free events are observed in the control arm. If PFS in the q12w arm is not significantly reduced, the remaining q9w, q15w and q18w arms will be opened. Pts who progress on a frequency reduced arm may re-escalate to q6w therapy. The primary objective is to determine the optimal continuing dose frequency of pembro, defined as the longest dose interval non-inferior to standard therapy using 2-year survival as the primary outcome. Secondary endpoints include OS, PFS, ORR, duration of response, adverse events, quality of life and cost effectiveness. An exploratory sub-study will explore fundamental aspects of cancer immunotherapy and develop novel biomarkers of response, resistance, toxicity and patient suitability for dose frequency de-escalation. Recruitment is ongoing and the trial is open at 16 centres at time of submission. Clinical trial information: NCT05085028 .

Phase I safety and preliminary efficacy of PM1003, a bispecific antibody targeting PD-L1 and 4-1BB, in patients with advanced solid tumors.

e14511 Background: PM1003 is a VHH-based anti-PD-L1/4-1BB bispecific antibody. The anti-4-1BB VHH arm binds to a unique epitope at the CRD4 region of 4-1BB, activating 4-1BB signals through cross-linking in the presence of PD-L1 that is often upregulated in the tumor microenvironment, thus avoiding harm to healthy tissues. This is the First In Human study of PM1003. Methods: This study was conducted with a standard 3+3 dose escalation design (Part A: single doses of 0.02, 0.1, 1, 3, 6, and 10 mg/kg for DLT evaluation after 3 weeks followed by Q2W for further administration) and dose expansion (Part B). For Part A, the primary endpoint was safety and tolerability with secondary endpoint of ORR per RECIST 1.1. For Part B, ORR per RECIST 1.1 was the primary endpoint and the secondary endpoints were safety and PK. Results: As of February 9, 2023, a total of 17 subjects have received at least 1 dose of PM1003, including 16 subjects in Part A (3 subjects in each of the 0.02, 0.1, 1, 3 mg/kg dose levels respectively and 4 subjects in 6 mg/kg), and 1 subject in Part B (1 mg/kg Q2W). In Part A, no DLTs were observed up to 6 mg/kg. Of the 17 patients, TRAEs occurred in 15 subjects (88.2%), ≥ Grade 3 TRAEs occurred in 5 subjects (29.4%). No patient discontinued PM1003 administration due to TRAE. The most common TRAEs were anaemia (35.3%), neutrophil count decreased (29.4%), white blood cell count decreased (29.4%), platelet count decreased (29.4%), fatigue (23.5%). 11 subjects completed at least one efficacy evaluation in part A. The median duration of PM1003 exposure was 9.9 weeks (range, 3.1-31.1 weeks). The ORR per RECIST 1.1 was 9.1% with a DCR of 54.5%. Preliminary evidence of antitumor activity has been observed in 1 subject with gastric cancer (1 mg/kg Q2W) who was enrolled after previous surgery, chemotherapy, anti-PD-1 and anti-HER2-ADC treatment, and had a partial response of 87.8% in target lesion reduction during the first efficacy evaluation (7 weeks) after PM1003 treatment. T1/2 of PM1003 of 1 mg/kg and 3 mg/kg dose level is 6.3 and 12.8 days, respectively. Receptor occupancy of PD-L1 in the 1 mg/kg and 3 mg/kg cohorts reached saturation at 336 hours after the first single dose and maintained at an almost stable state. Conclusions: PM1003 was well-tolerated up to 6 mg/kg and has shown preliminary anti-tumor activity in a patient who was previously treated with multiple drug modalities including anti-PD-1. The dose-escalation at 10 mg/kg and dose expansion are ongoing. Clinical trial information: ChiCTR2100052887 .

A phase 1, first-in-human, open-label, dose escalation and dose expansion study of TST005 in patients with locally advanced or metastatic solid tumors.

2531 Background: TST005 is a novel bi-functional fusion protein combining a high affinity PD-L1 mAb and a differentiated TGF-β trap with improved stability. In pre-clinical study, TST005 showed no antibody-dependent dependent cytotoxicity (ADCC) or complement dependent cytotoxicity (CDC) activity. Methods: This is a Phase 1, dose escalation study with classic 3+3 design to evaluate the safety, tolerability, PK and pharmacodynamic and preliminary anti-tumor activity of TST005 and determine the maximum tolerated dose and/or the Recommended Phase 2 Dose (RP2D). Eligible solid tumor patients who have failed prior standard therapy(ies) and have received no more than one prior immune checkpoint inhibitor (ICI) treatment will be enrolled to receive TST005 intravenous (IV) infusion every 3 weeks until disease progression assessed by the Investigator per RECIST v1.1 and/or immune RECIST, or unacceptable toxicity. Results: The study is ongoing at 4 clinical centers in US and China. As of 31 Jan 2023, 18 eligible subjects have been enrolled into different TST005 dose levels: 2 at dose of 1mg/kg, 4 at 3 mg/kg, 4 at 10 mg/kg, 3 at 20 mg/kg, and 5 at the last dose level of 30 mg/kg. The enrollment is still ongoing. No DLT was observed so far. The most common treatment-emergent adverse events (TEAEs) ( > 10%) included: fatigue (38.9%), rash (22.2%), anemia (16.7%), myalgia (16.7%), and arthralgia, dehydration diarrhea, dry skin, hematuria, hypokalemia, pruritus, lymphocyte count decreased were 11.1%. 7 patients (38.9%) experienced ≥Grade 3 (G3) TEAEs according to CTCAE V5.0, 1 of whom were considered as related to TST005: it was an infusion related reaction (G3), and caused discontinuation of treatment. Two subjects experienced IRRs (G2 and G3 respectively), both at the dose of 3mg/kg cohort. One subject of 30mg/kg dose cohort presented a squamous cell carcinoma of skin, which is known as a classic side effect of TGF-β directed therapies. The subject was discontinued from study and to receive resection. No treatment-related deaths occurred. TST005 demonstrated a nonlinear PK profile between 1 to 20 mg/kg with calculated t1/2 of 4-9 days. ADA was observed in most ADA evaluable subjects, PK at doses ≥ 10mg/kg were not impacted by ADA. At 20mg/kg, the receptor occupancy increased to > 90% immediately after infusion and remain at this level up to C2D1. Start from 1mg/kg, serum TGF-β1 was depleted immediately after dosing, sustained to next dose of TST005. 11 subjects had at least one post treatment tumor assessment per RECIST 1.1. 7 subjects (63.6%) had best overall response of SD. No PR or CR had been observed. Conclusions: TST005 monotherapy demonstrated a good safety and tolerability, nonlinear PK characteristics and significant target engagement in patients with advanced solid tumors. Continue investigation of TST005 as monotherapy or in combination with other therapies are warranted. Clinical trial information: NCT04958434 .

Sugammadex Is Not a Silver Bullet: Caveats Regarding Unmonitored Reversal.

Sugammadex Is Not a Silver Bullet: Caveats Regarding Unmonitored Reversal.

In vivo evaluation of a novel 18F-labeled PET radioligand for translocator protein 18 kDa (TSPO) in monkey brain

Purpose[18F]SF51 was previously found to have high binding affinity and selectivity for 18 kDa translocator protein (TSPO) in mouse brain. This study sought to assess the ability of [18F]SF51 to quantify TSPO in rhesus monkey brain.MethodsPositron emission tomography (PET) imaging was performed in monkey brain (n = 3) at baseline and after pre-blockade with the TSPO ligands PK11195 and PBR28. TSPO binding was calculated as total distribution volume corrected for free parent fraction in plasma (VT/fP) using a two-tissue compartment model. Receptor occupancy and nondisplaceable uptake were determined via Lassen plot. Binding potential (BPND) was calculated as the ratio of specific binding to nondisplaceable uptake. Time stability of VT was used as an indirect probe to detect radiometabolite accumulation in the brain. In vivo and ex vivo experiments were performed in mice to determine the distribution of the radioligand.ResultsAfter [18F]SF51 injection, the concentration of brain radioactivity peaked at 2.0 standardized uptake value (SUV) at ~ 10 min and declined to 30% of the peak at 180 min. VT/fP at baseline was generally high (203 ± 15 mL· cm−3) and decreased by ~ 90% after blockade with PK11195. BPND of the whole brain was 7.6 ± 4.3. VT values reached levels similar to terminal 180-min values by 100 min and remained relatively stable thereafter with excellent identifiability (standard errors < 5%), suggesting that no significant radiometabolites accumulated in the brain. Ex vivo experiments in mouse brain showed that 96% of radioactivity was parent. No significant uptake was observed in the skull, suggesting a lack of defluorination in vivo.ConclusionThe results demonstrate that [18F]SF51 is an excellent radioligand that can quantify TSPO with a good ratio of specific to nondisplaceable uptake and has minimal radiometabolite accumulation in brain. Collectively, the results suggest that [18F]SF51 warrants further evaluation in humans.

Proofreading does not result in more reliable ligand discrimination in receptor signaling due to its inherent stochasticity

Kinetic proofreading (KPR) has been used as a paradigmatic explanation for the high specificity of ligand discrimination by cellular receptors. KPR enhances the difference in the mean receptor occupancy between different ligands compared to a nonproofread receptor, thus potentially enabling better discrimination. On the other hand, proofreading also attenuates the signal and introduces additional stochastic receptor transitions relative to a nonproofreading receptor. This increases the relative magnitude of noise in the downstream signal, which can interfere with reliable ligand discrimination. To understand the effect of noise on ligand discrimination beyond the comparison of the mean signals, we formulate the task of ligand discrimination as a problem of statistical estimation of the receptor affinity of ligands based on the molecular signaling output. Our analysis reveals that proofreading typically worsens ligand resolution compared to a nonproofread receptor. Furthermore, the resolution decreases further with more proofreading steps under most commonly biologically considered conditions. This contrasts with the usual notion that KPR universally improves ligand discrimination with additional proofreading steps. Our results are consistent across a variety of different proofreading schemes and metrics of performance, suggesting that they are inherent to the KPR mechanism itself rather than any particular model of molecular noise. Based on our results, we suggest alternative roles for KPR schemes such as multiplexing and combinatorial encoding in multi-ligand/multi-output pathways.

Model-based Investigation of Inadequate Efficacy of Tesnatilimab, an Anti- Natural Killer Group 2 Member D (NKG2D) Monoclonal Antibody, in Moderately to Severely Active Crohn's Disease.

Tesnatilimab is a human immunoglobulin G4 isotype monoclonal antibody that blocks the natural killer group 2 member D (NKG2D) receptor and prevent the downstream signaling of proinflammatory cytokines and cytotoxic mediators. Subcutaneous tesnatilimab was investigated in a phase 2 randomized, double-blind, placebo-controlled trial in patients with moderately to severely active Crohn's disease (CD). While the proof-of-concept Part I of the study demonstrated significant treatment effects, Part II (dose-ranging) revealed unexpected lack of dose-response and a modest degree of clinical benefit for treatment groups. To inform further drug development, population pharmacokinetic (PopPK) modeling and exposure-response (E-R) analyses were planned and performed. A one-compartment PopPK model with first-order absorption and parallel linear and non-linear elimination pathways was established for tesnatilimab in CD patients. No clinically significant covariates were identified and overall consistent PK was observed between Part I and Part II patients. Receptor occupancy data suggested full occupancy of the peripheral blood NKG2D receptors and target engagement at all tested dose levels. Pooled Part I and Part II data showed a positive efficacy E-R relationship, however, this was driven by data from Part I. Part II only analysis did not show an apparent efficacy E-R relationship. No important covariates were identified in efficacy E-R analyses, overall and in various subpopulations. No apparent E-R relationships were observed for the investigated safety endpoints. The PopPK and E-R analysis indicated that the inadequate efficacy of tesnatilimab in CD was unlikely due to insufficient drug exposure and target engagement. This article is protected by copyright. All rights reserved.

Validation of a pharmacological imaging challenge using 11C-buprenorphine and 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography to study the effects of buprenorphine to the rat brain.

Buprenorphine mainly acts as an agonist of mu-opioid receptors (mu-OR). High dose buprenorphine does not cause respiratory depression and can be safely administered to elicit typical opioid effects and explore pharmacodynamics. Acute buprenorphine, associated with functional and quantitative neuroimaging, may therefore provide a fully translational pharmacological challenge to explore the variability of response to opioids in vivo. We hypothesized that the CNS effects of acute buprenorphine could be monitored through changes in regional brain glucose metabolism, assessed using 18F-FDG microPET in rats. First, level of receptor occupancy associated with a single dose of buprenorphine (0.1 mg/kg, s.c) was investigated through blocking experiments using 11C-buprenorphine PET imaging. Behavioral study using the elevated plus-maze test (EPM) was performed to assess the impact of the selected dose on anxiety and also locomotor activity. Then, brain PET imaging using 18F-FDG was performed 30 min after injection of unlabeled buprenorphine (0.1 mg/kg, s.c) vs. saline. Two different 18F-FDG PET acquisition paradigms were compared: (i) 18F-FDG injected i.v. under anesthesia and (ii) 18F-FDG injected i.p. in awake animals to limit the impact of anesthesia. The selected dose of buprenorphine fully blocked the binding of 11C-buprenorphine in brain regions, suggesting complete receptor occupancy. This dose had no significant impact on behavioral tests used, regardless of the anesthetized/awake handling paradigm. In anesthetized rats, injection of unlabeled buprenorphine decreased the brain uptake of 18F-FDG in most brain regions except in the cerebellum which could be used as a normalization region. Buprenorphine treatment significantly decreased the normalized brain uptake of 18F-FDG in the thalamus, striatum and midbrain (p < 0.05), where binding of 11C-buprenorphine was the highest. The awake paradigm did not improve sensitivity and impact of buprenorphine on brain glucose metabolism could not be reliably estimated. Buprenorphine (0.1 mg/kg, s.c) combined with 18F-FDG brain PET in isoflurane anesthetized rats provides a simple pharmacological imaging challenge to investigate the CNS effects of full receptor occupancy by this partial mu-OR agonist. Sensitivity of the method was not improved in awake animals. This strategy may be useful to investigate de desensitization of mu-OR associated with opioid tolerance in vivo.

Mechanistically Weighted Metric to Predict In Vivo Antibody-Receptor Occupancy: An Analytical Approach.

In situ clinical measurement of receptor occupancy (RO) is challenging, particularly for solid tumors, necessitating the use of mathematical models that predict tumor receptor occupancy to guide dose decisions. A potency metric, average free tissue target to initial target ratio (AFTIR), was previously described based on a mechanistic compartmental model and is informative for near-saturating dose regimens. However, the metric fails at clinically relevant subsaturating antibody doses, as compartmental models cannot capture the spatial heterogeneity of distribution faced by some antibodies in solid tumors. Here we employ a partial differential equation (PDE) Krogh cylinder model to simulate spatiotemporal receptor occupancy and derive an analytical solution, a mechanistically weighted global AFTIR, that can better predict receptor occupancy regardless of dosing regimen. In addition to the four key parameters previously identified, a fifth key parameter, the absolute receptor density (targets/cell), is incorporated into the mechanistic AFTIR metric. Receptor density can influence equilibrium intratumoral drug concentration relative to whether the dose is saturating or not, thereby influencing the tumor penetration depth of the antibody. We derive mechanistic RO predictions based on distinct patterns of antibody tumor penetration, presented as a global AFTIR metric guided by a Thiele Modulus and a local saturation potential (drug equivalent of binding potential for positron emissions tomography imaging) and validate the results using rigorous global and local sensitivity analysis. This generalized AFTIR serves as a more accurate analytical metric to aid clinical dose decisions and rational design of antibody-based therapeutics without the need for extensive PDE simulations. SIGNIFICANCE STATEMENT: Determining antibody-receptor occupancy (RO) is critical for dosing decisions in pharmaceutical development, but direct clinical measurement of RO is often challenging and invasive, particularly for solid tumors. Significant efforts have been made to develop mathematical models and simplified analytical metrics of RO, but these often require complex computer simulations. Here we present a mathematically rigorous but simplified analytical model to accurately predict RO across a range of affinities, doses, drug, and tumor properties.

Estrogenic Modulation of Ionic Channels, Pumps and Exchangers in Airway Smooth Muscle.

To preserve ionic homeostasis (primarily Ca2+, K+, Na+, and Cl-), in the airway smooth muscle (ASM) numerous transporters (channels, exchangers, and pumps) regulate the influx and efflux of these ions. Many of intracellular processes depend on continuous ionic permeation, including exocytosis, contraction, metabolism, transcription, fecundation, proliferation, and apoptosis. These mechanisms are precisely regulated, for instance, through hormonal activity. The lipophilic nature of steroidal hormones allows their free transit into the cell where, in most cases, they occupy their cognate receptor to generate genomic actions. In the sense, estrogens can stimulate development, proliferation, migration, and survival of target cells, including in lung physiology. Non-genomic actions on the other hand do not imply estrogen's intracellular receptor occupation, nor do they initiate transcription and are mostly immediate to the stimulus. Among estrogen's non genomic responses regulation of calcium homeostasis and contraction and relaxation processes play paramount roles in ASM. On the other hand, disruption of calcium homeostasis has been closely associated with some ASM pathological mechanism. Thus, this paper intends to summarize the effects of estrogen on ionic handling proteins in ASM. The considerable diversity, range and power of estrogens regulates ionic homeostasis through genomic and non-genomic mechanisms.

Cellular and In Vivo Preclinical Pharmacodynamics and Pharmacology of Nipocalimab, an Anti-FcRn Blocking Therapeutic Antibody (P10-5.011)

<h3>Objective:</h3> To characterize the mechanism of action, pharmacodynamics and pharmacology of nipocalimab in preclinical models. <h3>Background:</h3> Nipocalimab is a fully human antibody being evaluated in over 10 autoantibody diseases including MG and CIDP. Nipocalimab binds with high affinity to the neonatal Fc receptor (FcRn) inhibiting IgG recycling and inducing autoantibody destruction while permitting key immune functions including IgG production. Here, the molecular, cellular and in vivo pharmacology of nipocalimab are shown to be well aligned with the pharmacodynamic and pharmacological effects observed in MG patients. <h3>Design/Methods:</h3> Nipocalimab in vitro receptor occupancy (RO) was assessed in a fluorescence-activated cell sorting assay in human aortic endothelial cells. In vivo, RO in circulating monocytes and total serum IgG were evaluated in human FcRn transgenic mice (Tg32 strain) or cynomolgus monkeys after i.v. infusions of up to 100 or 300 mg/kg nipocalimab, respectively. <h3>Results:</h3> Nipocalimab exposure at picomolar concentrations results in full RO within 30 minutes and inhibits IgG recycling in endothelial cells. In vivo, full RO was established within 2 hours in mice and 4 hours in monkeys and maintained at picomolar concentrations. The onset of IgG lowering due to inhibition of IgG recycling was detected within 1–2 days and was maintained during the period of full FcRn saturation. Duration of RO in peripheral blood monocytes in both preclinical species was dose-dependent, as was the duration of IgG clearance, suggesting a relationship between RO and maintenance of an increased IgG clearance rate. Nipocalimab in vitro FcRn RO and IgG recycling correlated well with in vivo RO and IgG lowering. <h3>Conclusions:</h3> Nipocalimab is a potent FcRn blocker inducing rapid and sustained lowering of IgG and IgG autoantibodies in preclinical studies. These results are consistent with findings from the phase 1 healthy volunteer (NCT02828046) and phase 2 VIVACITY study in gMG patients (NCT03772587). <b>Disclosure:</b> Dr. Ling has received personal compensation for serving as an employee of Janssen Pharmaceuticals (Johnson&amp;Johnson). Dr. Ling has stock in Janssen Pharmaceuticals (Johnson&amp;Johnson). Dr. Ling has received intellectual property interests from a discovery or technology relating to health care. Dr. Ling has received intellectual property interests from a discovery or technology relating to health care. Dr. Choudhury has stock in Janssen Pharmaceuticals. Mr. Tyler has received personal compensation for serving as an employee of AVROBIO, INC . Mr. Tyler has received personal compensation for serving as an employee of Orna Therapeutics. Mr. Tyler has received personal compensation for serving as an employee of Genevant Sciences. Dr. Avery has received personal compensation for serving as an employee of Lyndra Therapeutics. Dr. Avery has received personal compensation for serving as an employee of Xilio Therapeutics. Dr. Avery has received personal compensation for serving as an employee of Kisbee Therapeutics. Dr. Avery has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Momenta Pharmaceutical. Dr. Avery has received stock or an ownership interest from Life Biosciences.

Schizophrenia Synaptic Pathology and Antipsychotic Treatment in the Framework of Oxidative and Mitochondrial Dysfunction: Translational Highlights for the Clinics and Treatment.

Schizophrenia is a worldwide mental illness characterized by alterations at dopaminergic and glutamatergic synapses resulting in global dysconnectivity within and between brain networks. Impairments in inflammatory processes, mitochondrial functions, energy expenditure, and oxidative stress have been extensively associated with schizophrenia pathophysiology. Antipsychotics, the mainstay of schizophrenia pharmacological treatment and all sharing the common feature of dopamine D2 receptor occupancy, may affect antioxidant pathways as well as mitochondrial protein levels and gene expression. Here, we systematically reviewed the available evidence on antioxidants' mechanisms in antipsychotic action and the impact of first- and second-generation compounds on mitochondrial functions and oxidative stress. We further focused on clinical trials addressing the efficacy and tolerability of antioxidants as an augmentation strategy of antipsychotic treatment. EMBASE, Scopus, and Medline/PubMed databases were interrogated. The selection process was conducted in respect of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Several mitochondrial proteins involved in cell viability, energy metabolism, and regulation of oxidative systems were reported to be significantly modified by antipsychotic treatment with differences between first- and second-generation drugs. Finally, antioxidants may affect cognitive and psychotic symptoms in patients with schizophrenia, and although the evidence is only preliminary, the results indicate that further studies are warranted.

Abstract CT174: First-in-class anti-CD200R1 antibody 23ME-00610 in patients with advanced solid malignancies: Phase 1 results

Abstract Background: CD200R1 was identified as a promising immuno-oncology (IO) target from the 23andMe database. Pleiotropic causal variants with opposing effect on risks for cancer and immune diseases, referred to as an IO signature, were observed in 3 components of the CD200R1 pathway. 23ME-00610 is a first-in-class monoclonal antibody that potently inhibits the CD200R1 immune checkpoint (KD less than 0.1 nM). The dose escalation portion of the first-in-human, Phase 1/2a study of 23ME-00610 (NCT05199272) has been completed and we are reporting data for the first time. Methods: Eligible patients were alteast 18 years with histologically diagnosed locally advanced (unresectable), or metastatic carcinoma or sarcoma who have progressed on standard therapies with ECOG 0 or 1. Key exclusion criteria included active autoimmune disease requiring immunosuppressive therapy and Grade 3 or above immune-mediated toxicity related to prior immunotherapy that led to discontinuation. Dose escalation consisted of accelerated titration (2 and 6 mg) followed by a 3+3 design (20, 60, 200, 600 and 1400 mg). Up to 12 participants were included in a PKPD backfill cohort at the recommended phase 2 dose (RP2D) or a previously evaluated dose level. Participants received 23ME-00610 intravenously every 3 weeks (Q3W) infused over 30 minutes. The primary objectives of Phase 1 were determination of the maximum tolerated dose (MTD)/recommended phase 2 dose (RP2D), safety and tolerability. Key secondary and exploratory objectives included pharmacokinetics (PK), pharmacodynamics (PD) and antitumor activity of 23ME-00610. Results: Between January 5th, 2022 and November 28, 2022, 21 participants (11/10 male/female; age range: 21-80 years) were enrolled and received ≥ 1 dose of 23ME-00610 across the 2 to 1400 mg cohorts (median duration of exposure: 50 days; range:1-231 days). No dose limiting toxicities, treatment related serious adverse events (TRSAEs) or AEs leading to discontinuation were observed. 14/21 (67%) participants experienced atleast 1 TRAE; the majority were Grade 1 or 2. The most commonly reported TRAEs occurring in atleast 2 participants across all dose levels were headache, fatigue, nausea and pruritis. There was 1 Grade 3 TRAE of increased blood creatinine phosphokinase. Investigator-assessed immune-related AEs including hypothyroidism, pruritis, fatigue and chills were observed at doses 60 mg and above. The PK of 23ME-00610 were dose-proportional at doses 60 mg and above, with a median terminal half-life of ~12 days at 1400 mg. Peripheral saturation of CD200R1 was observed at doses 60 mg and above, as measured by receptor occupancy on T cells and neutrophils, and levels of free soluble CD200R1. Analysis of additional PD data, including cytokines, is ongoing. Conclusion: 23ME-00610 demonstrated an acceptable safety and tolerability profile, with favorable PK and peripheral CD200R1 saturation. Increased immune-related AEs were observed at higher, pharmacologically relevant dose levels. Based on Phase 1 data, 1400 mg 23ME-00610 Q3W will be evaluated in Phase 2a. Citation Format: Shivaani Kummar, Albiruni ABDUL RAZAK, Scott Laurie, Sariah Kell, Dylan Glatt, Sophia R. Majeed, Drew Rasco. First-in-class anti-CD200R1 antibody 23ME-00610 in patients with advanced solid malignancies: Phase 1 results [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT174.

Abstract CT040: A first-in-human phase 1 trial of IO-108, an antagonist antibody targeting LILRB2 (ILT4), as monotherapy and in combination with pembrolizumab in adult patients with advanced relapsed or refractory solid tumors: Dose escalation study

Abstract Background: IO-108 is a fully human IgG4 monoclonal antibody with high affinity and specificity towards LILRB2 (also known as ILT4). It blocks the interaction of LILRB2 with the known ligands for LILRB2, including HLA-G, ANGPTLs, SEMA4A and CD1d. Methods: IO-108-CL-001 is a first-in-human, Phase 1a/1b study in patients with relapsed/refractory solid tumors (NCT05054348). The dose escalation phase enrolled patients into escalating dose cohorts of IO-108 (60-1800 mg, Q3W IV) as monotherapy or in combination with pembrolizumab. Patients with disease progression on monotherapy could crossover to the combination arm. Primary objectives were safety and tolerability, and identification of the recommended phase 2 dose (RP2D). Secondary and exploratory objectives include evaluation of pharmacokinetics (PK), immunogenicity, pharmacodynamic (PD) biomarker effects and anti-tumor activity as measured by objective response rate (RECIST 1.1). Results: Twenty-five relapsed/refractory solid tumor patients (median 4.5 prior lines of therapy for monotherapy and 3.6 for combination therapy) were treated with IO-108 monotherapy (n=12) or IO-108 + pembrolizumab (n=13). IO-108 was well-tolerated up to the maximal administered dose of 1800 mg Q3W as monotherapy and in combination with pembrolizumab, with no SAEs related to IO-108 and no DLTs observed. Maximum tolerated dose (MTD) was not reached. Full receptor occupancy through 21 days was achieved at ≥600 mg. The preliminary RP2D is 1200 mg Q3W. Dose-expansion cohorts of IO-108 monotherapy and IO-108 + anti-PD-1 are ongoing.Twenty-three patients were efficacy evaluable (11 monotherapy, 12 combination therapy plus 1 crossover). Overall response rate was 9% in monotherapy cohort (1 Merkel cell carcinoma, prior pembrolizumab followed by nivolumab/ipilimumab) and 23% in combination therapy (2 cholangiocarcinoma, 1 MSS CRC with neuroendocrine features)​. The best overall response was 1 CR, 4 SD among monotherapy, and was 3 PR, 4 SD among combination therapy.​ The 4 responding patients remain on study with an on-going treatment duration of 8 to 12 months as of abstract submission.Consistent with the MOA, clinical benefit correlated with baseline characteristics and post-treatment changes in PD biomarkers including reprogramming of myeloid cells and activation of T cells. Conclusion: The initial encouraging data support further development of IO-108, both as monotherapy and in combination with anti-PD-(L)1 for patients with advanced solid tumors. Citation Format: Matthew H. Taylor, Manish R. Patel, John D. Powderly, Paul Woodard, Luke Chung, Hongyu Tian, Xiang Hong, Kyu Hong, Donna Valencia, Tao Huang, Xiao Min Schebye, Charlene Liao, Aung Naing. A first-in-human phase 1 trial of IO-108, an antagonist antibody targeting LILRB2 (ILT4), as monotherapy and in combination with pembrolizumab in adult patients with advanced relapsed or refractory solid tumors: Dose escalation study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT040.

22. GM-2505 has Rapid Onset Antidepressant Activity and Causes Dose-Dependent Changes in qEEG With Increasing 5-HT2A Receptor Occupancy

22. GM-2505 has Rapid Onset Antidepressant Activity and Causes Dose-Dependent Changes in qEEG With Increasing 5-HT2A Receptor Occupancy

A phase 1 first-in-human study of GS-0189, an anti-signal regulatory protein alpha (SIRPα) monoclonal antibody, in patients with relapsed/refractory (R/R) non-Hodgkin lymphoma (NHL).

Signal regulatory protein alpha (SIRPα) is the receptor for cluster of differentiation (CD)47, a potent "don't eat me" signal for macrophages. Disruption of CD47-SIRPα signaling in the presence of prophagocytic signals can lead to enhanced phagocytosis of tumor cells, resulting in a direct antitumor effect; agents targeting this pathway have shown efficacy in non-Hodgkin lymphoma (NHL) and other tumor types. GS-0189 is a novel anti-SIRPα humanized monoclonal antibody. Here we report: (1) clinical safety, preliminary activity, and pharmacokinetics of GS-0189 as monotherapy and in combination with rituximab from a phase 1 clinical trial in patients with relapsed/refractory NHL (NCT04502706, SRP001); (2) in vitro characterization of GS-0189 binding to SIRPα; and (3) in vitro phagocytic activity. Clinically, GS-0189 was well tolerated in patients with relapsed/refractory NHL with evidence of clinical activity in combination with rituximab. Receptor occupancy (RO) of GS-0189 was highly variable in NHL patients; binding affinity studies showed significantly higher affinity for SIRPα variant 1 than variant 2, consistent with RO in patient and healthy donor samples. In vitro phagocytosis induced by GS-0189 was also SIRPα variant-dependent. Although clinical development of GS-0189 was discontinued, the CD47-SIRPα signaling pathway remains a promising therapeutic target and should continue to be explored.

Monitoring Cardiac Biomarkers with Aptamer‐Based Molecular Pendulum Sensors

AbstractReagent‐free electronic biosensors capable of analyzing disease markers directly in unprocessed body fluids will enable the development of simple &amp; affordable devices for personalized healthcare monitoring. Here we report a powerful and versatile nucleic acid‐based reagent‐free electronic sensing system. The signal transduction is based on the kinetics of an electrode‐tethered molecular pendulum—a rigid double stranded DNA with one of the strands displaying an analyte‐binding aptamer and the other featuring a redox probe—that exhibits field‐induced transport modulated by receptor occupancy. Using chronoamperometry, which enables the sensor to circumvent the conventional Debye length limitation, the binding of an analyte can be monitored as these species increase the hydrodynamic drag. The sensing platform demonstrates a low femtomolar quantification limit and minimal cross‐reactivity in analyzing cardiac biomarkers in whole blood collected from patients with chronic heart failure.